The invention described herein relates to a method of producing a living polymerized (co)polymer by polymerizing a polar unsaturated compound using an organic oxysalt compound as catalyst. These polymer and copolymer are very important ones as raw materials of polymer materials and functional polymers.
The invention relates particularly to compositions of thermosetting powder coatings, more particularly, to the compositions of thermosetting powder coatings having excellent storage stability (blocking resistance), external appearance (surface flatness, brightness, and transparency), physical property (hardness, scratch resistance, and recoating property), and chemical property (weather resistance, acid resistance, and solvent resistance) and to the compositions of thermosetting powder coatings which can provide baked coating films particularly suitable for use of coating vehicles.
Enormous number of researches have been made with regard to the polymerization of polar unsaturated compounds for many years. Among them, recently a number of researches on living polymerization catalysts have been conducted aiming at producing polymers having less narrow molecular weight distribution by controlling optionally and rigorously the molecular weight of polymers to be obtained and various polymerization catalyst systems have been developed which have the property of living radical polymerization, living anion or living coordination anion polymerization (for example, living radical polymerization catalysts: Koubunshi, vol.48, (7) pp 498-501 (1999); living anion and living coordination anion polymerization catalysts: Shin koubunshi Jikkengaku vol.2xe2x80x9cShin Koubunshi no Gouseixe2x80xa2Hannou(1)xe2x80x94Fukakei koubunshi no Gouseixe2x80x94xe2x80x9d pp 165-196, Kyouritu Shuppan Kabushikigaisha (1995)).
Many effective living polymerization catalysts have been developed and from the view point of xe2x80x9cthe number of produced polymer molecules corresponding to the number of molecules of polymerization catalyst usedxe2x80x9d in most cases only one polymer molecule is obtained from one molecule of polymerization catalyst, that is, stoichiometric polymerization is observed. This stoichiometric living polymerization requires one molecule of the polymerization catalyst to produce one polymer molecule which is not an efficient and effective method of production in the light of industrially practical use. On the other hand, in catalytic living polymerization wherein plural number of polymer molecules are produced by one molecule of polymerization catalyst it is possible to avoid or simplify the complicated processes of separating catalysts and control unfavorable effects on the polymer property to a minimum by reducing drastically the concentration of catalyst components remaining in the polymer produced. Furthermore, this method is a really practical one from the view point of reducing environmental load and catalyst cost. Actually, the polymerization catalyst systems of polar unsaturated compounds which have been practiced are composed of very small amount of radical generating agents (which mean the catalysts described herein) and a large amount of chain transfer agents. Although the polymerization does not proceed like living one, it produces very efficiently the number of polymer molecules comparable to the number of molecules of the chain transfer agents from one radical molecule.
The known examples of the catalytic living polymerization of polar unsaturated compounds are {circumflex over (1)} polymerization of methacrylate using alkali metal alkoxide as catalyst and alcohol as chain transfer agent (S. N. Lewis et al., Progress in Organic Coating 12, 1-26 (1984)) and {circumflex over (2)} polymerization of methacrylate and acrylate using quaternary ammonium salt or Lewis acid as catalyst and silyl ketene ketal as chain transfer agent (O. W. Webster et al., J.Am.Chem.Soc., 105, 5703 (1983) or Shin koubunshi Jikkengaku vol.2xe2x80x9cShin Koubunshi no Gouseixe2x80xa2Hannou(1)xe2x80x94Fukakei koubunshi no Gouseixe2x80x94xe2x80x9d pp 365-386, Kyouritu Shuppan Kabushikigaisha (1995)). However, the method {circumflex over (1)} is a good polymerization method for producing oligomers having average molecular weight of 500-3000 but cannot produce oligomers having average molecular weight greater than or equal to 3000 or (co)polymers by controlling their molecular weight and molecular weight distribution precisely. Furthermore, since this method uses alcohol as both chain transfer agent and polymerization solvent, transesterification proceeds simultaneously with polymerization. Therefore, there is a drawback that this method cannot apply to the monomers when the transesterification causes some problems. The method {circumflex over (2)} has not been practiced yet, because silyl ketene ketal is expensive and unstable and there are some problems in the production method.
As an important use utilizing the property of the (co)polymer which is obtained by the method of the present invention there are powder coatings and prior arts relating to them which will be explained in the following:
Solvent type coating materials have usually been used for painting bodies and those which satisfy various requirements have been developed and used in order to be utilized in the field of automobiles where rigorous quality specification is required.
Recently in the technical field of coating materials, shift to using powder coatings have been expected in place of solvent type coating materials in the light of local or global environment conservation, environment improvement of health and safety at work, prevention of fire and explosion, and resource conservation. And from the historical and social requests, as expectation for high function performance and diversification of powder coatings have been increased, high paint film performance (for example, weather resistance, acid rain resistance, and scratch resistance) of powder coatings comparable to solvent type coating materials have been requested. However, in spite of severe requests for paint film performance, powder coatings which satisfy these requests have not necessarily been placed on the market.
As specific examples of the conventional types of powder coatings there are those of epoxy resin and polyester resin. However, these coatings have not only problems in weather resistance but also in resistance against the acid rain which has recently become a particular problem and, therefore, these problems were regarded as critical in the field of painting automobile bodies.
For the purpose of eliminating the drawback, acrylic powder coatings was proposed in JP-B-48-38617 and remarkable improvement in weather resistance has been realized. Since then many researches have been made on the acrylic powder coatings, however, these acrylic powder coatings have not satisfied sufficiently external appearance property, physical property, chemical property, storage property, and particularly surface flatness and blocking resistance simultaneously. Reduction in melt viscosity is the most effective to improve the surface flatness, however, in order to reduce the melt viscosity it was necessary to lower a glass transition temperature by which method it was impossible to satisfy both the surface flatness and the blocking resistance.
For the purpose of providing the surface flatness and the blocking resistance simultaneously, thermosetting powder coatings composition (WO96/03464) is proposed which uses acrylic (co)polymer having narrow molecular weight distribution. It is surely possible to have the surface flatness and the blocking resistance simultaneously by narrowing the molecular weight distribution. However, according to the method of living polymerization which is described as an example of producing method of the acrylic (co)polymer used therein, due to the insufficient recoating property (adhesion property with top coatings at repainting and maintenance) the powder coatings, particularly as top coatings, did not show the effectiveness sufficiently. As another example of the production, an acrylic (co)polymer having the prescribed molecular weight distribution is shown by fractionating the acrylic (co)polymer obtained by radical polymerization method. However, in this method the proportion of the (co)polymer to be obtained as a target is low and a process of the fractionation is required, therefore, the method is costly and not practical. Researches on various living polymerization methods have been conducted for the purpose of narrowing the molecular weight distribution of acrylic (co)polymer, however, because of coloring, stench, and high cost of the acrylic (co)polymers produced there have not been the method of producing acrylic (co)polymers and thermosetting powder coatings which can favorably be applied to painting automobile bodies and parts for vehicles such as automobiles, particularly, painting of top coatings.
The purpose of the present invention is to provide a method of producing living (co)polymers effectively and efficiently by catalytic living polymerization of polar unsaturated compounds when (co)polymers are produced by the polymerization of polar unsaturated compounds.
Another purpose of the present invention is to provide thermosetting powder coating compositions (for example acrylic thermosetting powder coating compositions) having storage stability, external appearance property, physical property, and chemical property in the light of the problems described above; particularly to provide thermosetting powder coating compositions (for example acrylic thermosetting powder coating compositions) which are applied favorably to the painting automobile bodies and parts for vehicles such as automobiles (aluminum wheels, windshield wipers, pillars, door handles, fenders, bonnets, air spoilers, stabilizers, and front grilles), particularly, to the painting of top coatings.
As a result of the extensive and through researches to achieve the purposes described above, the inventors of the present invention have completed the present invention by finding out that by a method of polymerization of polar unsaturated compounds using an organic oxysalt compound as catalyst in the presence of a hydroxycarbonyl compound having at least both an alcoholic hydroxyl group and a carbonyl group in the same molecule the polymerization has the property of stoichiometric or catalytic living polymerization and it is possible to control precisely not only the average molecular weight of the (co)polymer produced but also the number of the molecules of the (co)polymer.
That is, the present invention is a method of producing a living polymerized (co)polymer comprising polymerization of polar unsaturated compound using organic oxysalt compound as catalyst in the presence of a hydroxycarbonyl compound having at least both an alcoholic hydroxyl group and a carbonyl group in the same molecule when producing the (co)polymer by (co)polymerization of polar unsaturated compounds using oxysalt compound as catalyst.
Furthermore, as a result of more extensive and through researches to resolve the problems of the prior arts as described above, the inventors found out the knowledge that by using the (co)polymer(A) as described above it is possible to provide a thermosetting powder coating composition having excellent storage stability, external appearance, physical property, and chemical property (for example, an acrylic thermosetting powder coating composition) and completed the present invention.
The present invention is specified by items as described in the following [1]-[17]:
[1] A method of producing a living polymerized (co)polymer which method comprises polymerization of polar unsaturated compound in the presence of a hydroxycarbonyl compound having at least both an alcoholic hydroxyl group and a carbonyl group in the same molecule using an organic oxysalt compound as catalyst.
[2] The method as described in [1], wherein a cation forming the organic oxysalt compound is an alkali metal cation, a tetraalkylammonium cation, a trialkylsulfonium cation, a tetraarylphosphonium cation, a hexaarylphosphoranilidene ammonium cation, or a tetrakis{tris(dialkylamino)phosphoranilideneamino}phosp honium cation.
[3] The method as described in [1], wherein the cation forming the organic oxysalt compound is a tetraalkylammonium cation, a tetraarylphosphonium cation, or a hexaarylphosphoranilidene ammonium cation.
[4] The method as described in any one of [1] to [3], wherein an anion forming the organic oxysalt compound is an organic oxyanion derived from a monohydric alcohol, an organic oxyanion derived from a monocarboxylate, or an organic oxyanion derived from a polycarboxylate.
[5] The method as described in any one of [1] to [3], wherein an anion forming the organic oxysalt compound is an organic oxyanion derived from a monohydric alcohol.
[6] The method as described in any one of [1] to [5], wherein the hydroxycarbonyl compound is an xcex1-hydroxyketone or an xcex1-hydroxycarboxylate.
[7] The method as described in any one of [1] to [6], wherein the polar unsaturated compound is a chemical compound having both a polar functional group selected from carbonyl, cyano, or pyridyl groups, and an unsaturated group in the same molecule and, in addition, the functional group and the unsaturated group form a direct or indirect conjugated system.
[8]
The method as described in any one of [1] to [6], wherein the polar unsaturated compound is a (meth)acrylate, a (meth)acrylonitrile, a (meth)acrylamide, a vinylpyridine, a N-substituted maleimide, a vinylketone, or a styrene derivative.
[9] The method as described in any one of [1] to [6], wherein the polar unsaturated compound is a monoester between a monohydric alcohol and acrylic acid or methacrylic acid, a monoester between acrylic acid or methacrylic acid and a dihydric alcohol one end of which is protected by ether linkage, a polyester formed by esterification between acrylic acid or methacrylic acid and all of the hydroxyl groups of the polyhydric alcohol, having two or more hydroxyl groups, an acrylonitrile, a methacrylonitrile, a N,N-disubstituted mono(meth)acrylamide, a pyridine substituted by vinyl or isopropenyl group, a N-aromatic substituted maleimide or a vinylketone.
[10] The method as described in any one of [1] to [9], wherein an active hydrogen compound is used as chain transfer agent.
[11] The method as described in any one of [1] to [9], wherein the chain transfer agent is a , monocarboxylate, a polycarboxylate, a monohydric alcohol, a polyhydric alcohol, a monothiol, a (co)poly(alkyleneoxide) having an active hydrogen at its end and/or in its backbone chain, a (co)poly{(meth)acrylate)}, a (co)poly{(meth)acrylonitrile)}, a (co)poly{(meth)acrylamide}, a (co)poly(vinylpyridine), a (co)poly(N-substituted maleimide), a (co)poly(vinylketone), or a (co)poly(styrene derivative).
[12] The method as described in any one of [1] to [11], wherein the copolymer is produced by using at least two or more of the polar unsaturated compounds together.
[13] A thermosetting powder coating composition comprising;
a living polymerized (co)polymer (A) obtained by the method as described in any one of [1] to [12] and
a curing agent composition component(B) which can cure said (co)polymer.
[14] The thermosetting powder coating composition as described in [13], wherein the (co)polymer(A) comprises an epoxy group.
[15] The thermosetting powder coating composition as described in [13] or [14], wherein the (co)polymer(A) has a glass transition temperature of 10xc2x0 C.-100xc2x0 C.
[16] The thermosetting powder coating composition as described in any one of [13] or [15], wherein the curing agent composition component(B) which can cure the (co)polymer comprising;
(b-1) a polycarboxylic acid and/or
(b-2) a polycarboxylic acid anhydride.
[17] The thermosetting powder coating composition as described in any one of [13] to [16] wherein the thermosetting powder coating composition is for use as top coating of automobiles.